Answer:
a. 14000
Explanation:
Given parameters:
Efficiency of the machine = 70%
Work done on machine = 20000J
Unknown:
Work done by machine = ?
Solution:
Efficiency of a machine is determined by;
Efficiency =
70 =
x 100
70 =
Work done by machine = 70 x 200 = 14000J
This can be calculated with the law of conservation of energy. The kinetic energy Ek of the train is completely transformed to potential energy of the spring Ep which stops the train:
Ek=Ep
(1/2)*m*v²=(1/2)*k*x², where m is mass of the train, v is the velocity of the train, k is the force constant of the spring and x is the path the train went while being stopped and also the amount of length the spring compressed.
We solve for k:
(1/2)*m*v²=(1/2)*k*x², 1/2 cancel out:
m*v²=k*x², we divide both sides by x² and get k:
k=(m*v²)/x²={(5*10^5)*(0.5²)}/(0.4²)=781250 N/m
So the force constant of the spring is: k=781250 N/m.
Answer:
The atomic number tells you your protons a neutrons and you can find electrons by doing the atomic mass minus the atomic number
Explanation:
MAN
Mass-Atomic Number=Nuetrons
Answer:
(a) Electrostatic force F=4.51×10⁻¹⁷N
(b) Number of electron n=4425 electrons
Explanation:
Given data
Charges q₁=q₂= -7.08×10⁻¹⁶C
Distance r=1.00cm =0.01 m
To find
(a) Electrostatic force F
(b) Number of electron n
Solution
For (a) Electrostatic force
From Coulombs law we know that

For (b) number of electron n
The number of electron on the drop that giving it its imbalance is the total charge divided by charge of electron
As we now that charge of electron e= -1.6×10⁻¹⁹C

<h2>
<u>KINETIC ENERGY</u></h2>
<h3>Problem:</h3>
» A 2kg mass is moving at 3m/s. What is its kinetic energy?
<h3>Answer:</h3>
— — — — — — — — — —
<h3>Formula:</h3>
To calculate the velocity of a kinetic energy, we can use formula
where,
- v is the velocity in m/s
- KE is the kinetic energy in J (joules)
- m is the mass in kg
— — —
Based on the problem, the givens are:
- KE (Kinetic energy) = ? (unknown)
- m (mass) = 2 kg
- v (velocity) = 3 m/s
<h3>Solution:</h3>
To get the velocity, substitute the givens in the formula above then solve.

Therefore, the kinetic energy is 9 Joules.